In advance of performing a process for connecting an electronic component to a wiring board having an electric circuit wiring area thereon, a curable resin solution composition is applied on a certain area of the electric circuit wiring area to give a coated film, and then the coated film is heated to give an insulating cured film.
Document 1 (JP-A-2002-12664) describes a polyimidesiloxane solution composition employable for formation of an insulating film (protective film, solder resist, interlayer insulating layer, etc.) which is used in an electronic component packaging. The polyimidesiloxane solution composition contains polyimidesiloxane soluble in an organic solvent and a curable component such as an epoxy compound and/or a polyvalent isocyanate compound. The solution composition can be well coated on a substrate such as a flexible wiring board by a screening printing method, and the coated layer can be heated at a relatively low temperature to give an insulating cured film. Thus formed insulating cured film is closely attached to the substrate and does not bring about warpage of the substrate. Moreover, the insulating cured film is good in all of heat resistance, resistance to solvents, resistance to chemical materials, flexing resistance, and electric performance. Accordingly, the solution composition is favorably employable for forming an insulating cured film (protective film) for the purpose of protecting a flexible wiring board such as TAB (Tape Automated Bonding) tape or a flexible wiring board. The above-mentioned polyimidesiloxane soluble in an organic solvent is prepared by the reaction of an aromatic tetracarboxylic acid compound, a diaminopolysiloxane component, and an aromatic diamine compound having a polar group.
Document 1 further describes that a defoamer can be optionally added to the polyimidesiloxane solution composition. There are described examples of the defoamers such as an acrylic defoamer, an acrylvinyl ether defoamer, a fluorine-containing defoamer, and a silicone defoamer. As examples of the silicone defoamers, there are mentioned dimethylpolysiloxane defoamers of a solution type and an oil-compound type (e.g., KS-603 available from Shin-Etsu Chemical Industry Co., Ltd., and DB-100 available from Dow-Corning Corp.). The defoamer used in the working examples is Floren AC326F (i.e., acrylvinyl ether defoamer).
Heretofore, the electro-conductive connection of an electronic component to a wiring board has been made by the use of solder or a bump of an electro-conductive material such as gold. Recently, however, an anisotropic conductive material such as an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) has been used for attaching an electronic component such as a liquid display component to a wiring board. The electronic connection is formed via an outer lead of the wiring board.